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OLED displays

Date issued:02/03/2010

What is OLED?

An organic light-emitting diode (OLED), is as the name suggests a light-emitting diode made of organic compounds. Often referred to as a light emitting polymer (LEP), an OLED is for all intents and purposes the next-generation of LEDs - the lights surrounding us in everyday life through various devices such as TVs, clocks and signs.

Unlike traditional LEDs, the OLED variety feature layers of organic, light-emitting material placed between an anode and a cathode. When an electric current is passed through, the recombining of electrons and electron holes cause the organic layer to emit a brilliant white light. That, of course, is a gross simplification of a technology that involves the precise manipulation of electrons, but it gives readers a basic idea.

Putting them into practise, numerous OLEDs - produced using varying organic materials to create different colours - are then combined in an array to form a matrix of pixels that create a colour display.

As is the case with current-generation LCD displays, OLEDs are most commonly produced in two varieties - Passive Matrix (PMOLED) and Active Matrix (AMOLED). Although the working principal of each OLED variety remains similar, they differ in the arrangement of pixels. An AMOLED will generally feature an array of OLEDs printed onto a thin film transistor (TFT). AMOLED displays are considered to have greater potential and offer sunlight readability, ultra-fast response times, ultra-high contrast ratios and exceptional viewing angles.

What are the benefits?

Knowing what an OLED is, you may believe it to be awfully similar to a traditional LED. Although both live to achieve a similar goal - producing light - there are notable benefits to OLED.

First and foremost, OLEDs feature emissive layers that can themselves produce light. This technology eliminates the need for a backlight and an OLED display is consequently more energy efficient and less likely to produce large amounts of heat.

Furthermore, without the need for a backlight and with diodes constructed of just a few thin layers, OLED technology allows for the construction of incredibly thin displays. Even at this early stage, OLED TVs are known to measure as little as 3mm, far thinner than even the most modern LCD/Plasma panels.

Despite their ultra-slim dimensions, OLED TVs are also capable of producing a far better image than either LCD or Plasma alternatives. Thanks to the brilliant light produced by the organic material, OLED displays are able to provide incredible contrast ratios, vivid colours, improved brightness, a much faster response time, a near-limitless viewing angle and an overall sharper image.

On top of all that, the thin nature of OLEDs allow for them to be printed onto varying forms of material - paving the way for ultra sharp, colour displays that are flexible and almost paper like.

Are there any disadvantages?

OLEDs sound too good to be true, but there are a few drawbacks you'll need to be aware of.

The most obvious drawback is the limited lifespan of the organic material used. As an example, one of the first widely-available OLED TVs - the Sony XEL-1 - has a quoted lifespan of approximately 30,000 hours. That equates to a life of just over 10 years if used for eight hours per day. Sounds plentiful, but it's about half the lifespan of an LCD screen.

Although manufacturers are quickly showing success in extending the lifespan of OLED TVs through new technologies, another disadvantage that remains is cost. Despite the obvious performance benefits, OLED technology remains expensive to manufacture and TVs based on the technology are consequently wildly expensive.

Closing thoughts

The benefits of OLED technology are clear to see (excuse the pun), and the promise of a brighter, sharper and more vivid image, combined with lower energy consumption, clearly has widespread appeal.

Although the technology is seen as the logical successor to LCD and Plasma TVs, OLED displays are also becoming increasingly popular in mobile form factors. Today, a handful of mobile phones - including the Nokia N85 and Samsung Jet - incorporate OLED displays under 4in in size. Similarly, the Zune HD portable media player from Microsoft features a 3.3in OLED display.

Although it may be some time before OLED TVs are widely available in big-screen form factors at prices able to rival current LCDs, the technology continues to hold a lot of potential. Expect to see and hear a lot more about OLED technology in the coming years.